How do you Split Action strips?
If the Action strips are NLA-enabled:


Select the action in the NLA.
From the NLA menu, select Edit ->> Split Strips (Y is the default shortcut).


If they aren't NLA-enabled:


In the Action Editor, create a new action by clicking the '+' symbol next to the action to duplicate the action.





Select the newly duplicated action, and edit out the keyframes from the first part of the action, and label it whatever the later action is called (ie) 'Jump').